1. Technical Field
The invention relates to a device for handling material, especially soil, the device consisting of a bucket of a machine having a grinding device for material fitted thereto, the grinding device comprising at least two essentially parallel shafts which are at a distance from each other and rotatable in synchronization, the shafts comprising grinding members for the material, whereby the grinding members of two adjacent shafts overlap each other, the bottom of the bucket comprising an outlet opening for the handled material.
2. Background Art
The materials to be handled include, in particular, different soils such as compost, peat, and waste soil as well as different waste materials.
The bucket of the above described type which is especially intended to be used as the bucket of an excavator and for grinding soil, is known from FI patent application 902469. The grinding members on the shafts of the grinding device in this known bucket construction consist of radial blades welded on the shafts which mix and grind the soil to be handled. A disadvantage of this construction is that the blade can be twisted by stones or the like resulting in the twisted blade colliding with the blade on the adjacent shaft, whereby the bucket must be stopped and removed for repair. Another disadvantage of the described construction is that roots or the like can become tangled with the blades resulting in jamming the device. The handled soil would not be very loose, either, nor would it be sufficiently high-quality for demanding uses.
3. Disclosure of the Invention
Screening plants are also well known which handle compost using large drum screens. Such plants are very expensive and require separate transporting equipment if they are to be transferred from one place to another.
The purpose of this invention is to provide a device which avoids the above-described drawbacks of known devices, and the purpose of the invention is namely to provide a device which is very reliable and comprises a minimum number of parts which wear and are apt to break, and which, in addition to effectively screening and grinding the material to be handled, also renders it a loose form.
An important object of the invention is thus to provide a device which produces very high-quality soil which suits demanding uses very well.
These objects can be realized by the device according to the invention, the main characteristics of which are disclosed in the appended Claims.
The invention is based on the realization that a bucket construction is provided comprising a grinding device which includes effective and strong grinding members and which screens and grinds the material to be handled, and a loosening device which renders the screened and ground material in a loose form resulting in very high-quality material.
Thus the bucket according to the invention, which preferably is a bucket of a wheel loader, comprises a grinding device for the material fitted to the bucket, the grinding device including at least two, preferably four, essentially parallel shafts which are at a distance from each other and rotatable in synchronization and which comprise grinding members for the material consisting of numerous discs which are spaced from each other on each shaft, the discs having projections on the peripheral surface thereof, whereby a notch is provided between two adjacent projections. The grinding members of the two adjacent shafts overlap each other. The bottom of the bucket is provided with an outlet opening for the handled material.
As described above, the bucket according to the invention further comprises a loosening device which is fitted between the grinding device and the outlet opening and which comprises at least two, but preferably two, essentially parallel shafts which are spaced from each other and rotatable in synchronization, including aeration blades for loosening the ground material. The aeration blades are preferably shaped like propellers.
According to the invention, also a bar screen can be fitted into the bucket which screens, for example, stones, stubs, roots and similar large-sized items out of the compost. Such a bar screen is fitted above the shafts of the grinding device, preferably so that the ribs of the bar screen are between the planar parts of the overlapping discs.
The above-mentioned discs preferably comprise an essentially tooth-like shape and according to a preferred embodiment of the invention, the teeth comprise a widening part extending from the tooth to the notch situated after the tooth in the direction of rotation of the disc.
According to the invention, the shape of the shafts of the grinding device is preferably polygonal, especially preferably hexagonal, whereby the discs comprise a corresponding polygonal bore. This construction ensures that the discs are rotated along with the shaft.
In order to keep the desired distance between the discs on the same shaft, a spacing sleeve with a length corresponding to the desired distance between the discs can be fitted between the discs and around the shaft.
The grinding device and the loosening device are driven by hydraulic motors which are connected to the hydraulic system of the machine. The shafts of the grinding device are advantageously rotated in the same direction, the speed of rotation being typically about 100 to 150 rpm. The shafts of the loosening device are rotated at a considerably higher velocity than the shafts of the grinding device, the typical speed of rotation being about 400 to 500 rpm. Depending on the construction of the aeration blades, the shafts of the loosening device can be rotated either in the same direction or in different directions.